Transmission electron microscopy (TEM) is a method for presenting and analysing miniaturized objects having a size of an order of magnitude of a few nanometres. TEM is used, for example, for analysing integrated switching elements. To this end, the object to be examined must be sufficiently thin to allow electrons of an electron beam to penetrate the object, i.e. to be transmitted by the object. In addition, the entry surface, at which the electron beam is incident on the object, and the exit surface, at which the electron beam exits the object again, should be as smooth as possible, i.e. have the lowest possible roughness. In some cases, the entry surface and the exit surface should be as parallel to one another as possible. However, there are applications in which the object to be examined and thus the entry and exit surfaces are to have a different form. An object that meets these requirements is suitable for analysis using TEM and will be referred to below as a TEM sample.
For producing TEM samples, particle beam systems having an ion beam column and an electron beam column are typically used. The ion beam column is used to process the object, while the electron beam column is used to produce images of the object and thus to monitor the object. For positioning and orienting the object in relation to the ion beam column and the electron beam column, a positioning apparatus is used. For example, the positioning apparatus includes a sample stage having three translational degrees of freedom and two rotational degrees of freedom for positioning and orientating the object relative to the ion beam column and the electron beam column. The positioning apparatus frequently includes further auxiliary constructions, which are arranged on the sample stage and provide further degrees of freedom for moving the object. These auxiliary constructions must be manufactured mechanically with great precision, imply further controlling outlay and further potential error sources in the positioning and orienting of the object.
It is therefore desirable to be able to produce TEM samples without the need to use such auxiliary constructions.
US 2014/0 190 934 A1 discloses a method and an apparatus for preparing samples for observation in a system with charged particle beams in a way that reduces or prevents artifacts. Material is deposited onto the sample using charged particle beam deposition just before or during the final milling, which results in an artifact-free surface. Embodiments are useful for preparing thin TEM samples.
US 2017/0 256 380 A1 discloses techniques that facilitate automated extraction of lamellae and attaching the lamellae to sample grids for viewing on transmission electron microscopes.
US 2015/0 001 176 A1 discloses a method and an apparatus for altering the orientation of a sample that is processed and analysed using a particle beam system.
C. Li et al., “An improved FIB sample preparation technique for site-specific plan-view specimens: A new cutting geometry”, Ultramicroscopy 184 (2018), pages 310 to 317, discloses FIB Lift-Out sample preparation.
L. A. Giannuzzi et al., “A review of focused ion beam milling techniques for TEM specimen preparation”, Micron 30 (1999), pages 197 to 204, discloses methods for producing transmission electron microscope samples using a focused ion beam.